An award-winning teen fantasy-mystery.

Described by fans as "complex", "intriguing", "imaginative", “gripping”, and “Harry Potter-like”.

Thousands of children disappear from our world. No one sees the kidnapping; or if they do, they forget. But one toddler returns after a week, riding a wolf with a falcon circling over him. That boy is Will Cleary.

Will tries to live a normal life. But his twin sister is still missing, and their parents never stop searching for her. Then, just before his 13th birthday, Will's pets reveal a secret to him. (Though how it happens will remain a secret, until you listen to the audiobook.)

A hidden world lies beneath our feet, a land filled with see-through trees and lucent people. They call us Sounds, and they are our Echoes; for each one of them is a reflection of one of us. It is a sparkling, beautiful place, a winter wonderland. But there is evil there, a terrible law, the law of death.

When a Sound dies in our world, his Echo is executed in Echoland. And there are those who reverse the order of things to achieve their wicked ends. They hunt the Sound of the Echo they want to kill. Then, the first death leads to the second as surely as lightning leads to thunder.

Is that what happened to the missing children in Will's realm? Did someone want to murder their Echoes? Or are these Sounds still alive, trapped somewhere in Echoland?

Will tries to escape the frightening answer. But dangers sweep him into that magical, see-through land. And there, in a fortress filled with castaway children, a 200-year-old riddle lies buried. The most important boy in Echoland will help Will solve it, with a handful of other kids. For the fate of Echoland, and of the Sound realm, depends on the answer.

An answer hidden in an ancient book...deep in a frozen lake of gems...beyond a buried door...at the foot of the greatest Crystillery of all.

But many men and monsters, crystal balls and spying eyes, will try to stop the brave teens. For how see-through your skin is is all-important in Echoland. And when this ancient hate will end, the realm of the Echoes will change forever.

"A young hero must ally with his alter ego in an intricate parallel universe in order to rescue his sister and save his own life. A gripping...fantasy coming-of-age novel." (Kirkus Reviews)

Winner of seven book awards.